The invention relates to a photopolymerizable mixture. More particularly, the invention relates to a mixture which comprises a polymeric binder, a polymerizable compound having at least one terminal olefinic double bond and having a boiling point above 100.degree. C. at normal pressure, and a 9-arylacridine compound as photoinitiator.
DE-C-2,027,467 discloses photopolymerizable mixtures of the composition specified above which contain derivatives of acridine and phenazine as photoinitiators. Some representatives of this class of compound, for example 9-phenylacridine, are notable for a high photosensitivity. The preferred representatives have the disadvantage that they tend to migrate out of photopolymerizable coatings which are in contact with polyethylene films into said films and through them. As a result, the coating becomes depleted of initiator and loses sensitivity. The initiator may also migrate out of photocured photoresist coatings into certain treatment baths, for example acidic electroplating baths and produce a troublesome yellow coloration therein.